Air conditioning system



Feb. 24, 1942. c. w. NESSELL 2,274,514

AIR CONDITIONING SYSTEM Filed Sept. 19, 194Q ATTORN EY Patented Feb. 24, 1942 AIR CONDITIONING SYSTEM Clarence W. Nessell, Cleveland, Ohio, assignor to Minneapolis-Honeywell Regulator Company, Minneapolis, Minn., a corporation of Delaware Application September 19,1040, Serial No. 357,259

7 Claims.

This invention relates to fluid circulating systems, in general, and more particularly to fluid circulating means for warm air heating systems.

In a building having a plurality of spaces or zones to be heated, it is common toprovide a warm air furnace connected by ducts to the various zones, and a blower for circulating air through the furnace and the zones. In order to 1 control the temperature in each zone individually, each zone may be provided with a thermostat controlling a motor which operates a damper in the duct leading to the zone, so as to permit or prevent the flow of warm air to the zone in accordance with the air temperature in the zone.

In such a system, it is unnecessary to circulate air as rapidly when one zone is calling for heat as when more than one zone calls for heat. In the present invention, I therefore provide, for a two-zone heating system, means to operate the blower so as to circulate air at one rate when only one zone is demanding heat, to circulate air at a greater rate when two zones demand heat,

and also to stop the blower when none of thezones is demanding heat. When none of the zones is demanding heat, there is no need for operation of the blower, since all the zone dampers are closed.

The present invention is an improvement on the system disclosed in my co-pending application No. 161,591, filed August 30, 1937, and issued as Patent No. 2,223,295, dated November 26, 1940. In that application I disclosed a circuit for controlling the speed of a blower in a system having any number of zones. The present invention is a more simplified, less expensive system, which is particularly adapted to control the speed of a. blower in 'a heating system having only two zones.

One of the objects of my invention is to provide improved fluid circulating apparatus for a twozone air conditioning system. I

Another object of the invention is to provide a simple and inexpensive control circuit for a two-speed blower when used in a two-zone air conditioning system.

O.her objects of the invention will become apparent upon a study of the following specification and claims and the appended drawing.

The single figure of the drawing represents diagrammatically a two-zone air conditioning system embodying the improved control means of my invention.

A furnace I is shown in the drawing and. a fan H is provided to' force the circulation of, air through the bonnet of the furnace.

Air is discharged through a main duct l2 and smaller delivery ducts l3 and I4 into the zones l5 and [6. A bimetallic thermostat I1 is located in the zone I5 and operates a switch arm l8 between stationary contacts 19 and 20. A similar thermostat 26 is located in zone l6 and operates a switch arm 21 between stationary contacts 28 and 29.

The furnace I0 is shown as of the gas burn-' ing type although it may be of anysuitable construction. The supply of gas to the main burner 30 of the furnace is controlled by an electrically operated valve 3|. Gas is supplied to a pilot burner 32 through a pipe 33 which by-passes the valve 3|. A bimetallic safety switch 34 is located. adjacent the flame of the pilot burner 32. A

' thermostat 35 mounted in the bonnet of the furnace operates a fan switch 36 and. a limit switch 3'! in accordance with the temperature of the air in the bonnet.

The air flowing out of the furnace through the main duct I2 is divided between the smaller ducts l3 and I l. The flow of air through the duct 13 is controlled by a damper 40 which is operated between open and closed positions by a damper motor 4| connected to the damper 40 by any suitable linkage. The damper motor 4| also drives a cam42 which actuates, a switch arm 43. The switch arm 43 is normally biased against a lower contact 44 but may be actuated by the cam to disengage from contact 44 andengage an upper contact 45.

The flow of air through the duct I4 is controlled by a damper similar in all respects to the damper 40 and operated by damper motor 5|. The dampermotor 5| also operates a cam I 52 which controls the position of the switch arm 53. This switch arm 53 is normally biased against a lower contact 54 but may be moved by the cam 52 so as to engage with an upper contact 55;

The connections between cams 42 and 52 and 7 their associated damper motors are such that the cams are rotated through degrees whenever operating two switch-arms 62 and 63. When the winding BI is energized, these switch arms engage stationary contacts 64 and 65, respectively.

The fan II is of a type which may be driven at two different speeds and a second relay 66 is provided for controlling the speed at which the fan is operated. This relay 68 comprises a Winding 61 operating a switch arm 68. Switch arm 68 engages a stationary contact 89 when the winding 61 is energized and engages a stationary contact I8 when the winding 61 is deenergized.

Power is supplied to operate this control system through lines 7| and 12. The energizing circuit for the fan I may be traced from line H through a conductor 13, the fan H and thence through either conductor 14 and contact 69 or through conductor 15 and contact 18 to the switch arm 68.

The circuit may then be traced from switch arm 68 through a conductor 76, fan controlling switch 36, a conductor 17, contact 65, switch arm 63, and a conductor 18 to the line 12. The internal construction of the motor of fan H is such that the fan is operated at a low speed when its energizing circuit is completed through conductor 14 and contact 69, and at a high speed when the circuit is completed through conductor 15 and contact 78.

The main supply valve 3| is energized from a circuit supplied by a transformer 79 having a primary winding 88 connected to the supply lines ll and i2 and a secondary winding 8|. This circuit may be traced from the left-hand end of secondary winding 8|, as it appears in the drawing, through conductors 82' and 83, switch arm 62, contact 64,.conductor 84, limit switch 37, a conductor 85, safety switch 34, a conductor 86, main supply valve 3|, and conductors 81, 88, and 89 to the right-hand terminal of secondary wind- The energization of relay 68 is controlled by a circuit which extends from the left-hand end of secondary winding 8| through conductors 82 and 83, relay winding SI, and then either through conductor 98, switch contact 45, switch arm 43 and conductors 81 and 88 or through conductor 9|, contact 55 and switch arm 53 to conductor 89 and thence to the right-hand end of transformer winding 8| The energization of relay winding 66 iscontrolled by a circuit which may be traced from the left-hand end of secondary winding 8| through conductors 82 and 83, relay winding 61, and then either through, a conductor 92, contact 44, switch arm 43, and conductors 81 and 88, or through a conductor 93, contact 54, and switch arm 53 to conductor 89 and thence to the right-hand end of secondary winding 8|. 7

It will be seen, therefore, that relay winding 6| is energized whenever either of switch arms 43 and 53 engages its associated upper contact, and that relay winding 61 is energized whenever either of switch arms 43 and 53 engages its lowe contact.

The damper motors 4| and 5| are energized from the transformer secondary winding 8| through lines 82, 88, and 89. These damper motors are controlled respectively by the zone thermostats l1 and 26. Contacts 9 and 28 of thermostat H are connected to damper motor 4| by conductors I88 and NH, respectively. The bimetallic element of thermostat I! is also connected to damper motor 4| through a conductor I82. The thermostat 26 is similarly connected to damper motor 5| through conductors |83,||84, and I85. Both the thermostats are constructed so as to move their switch arms against the lefthand contact when the temperature within the zone drops below the value which it is desired to maintain and move their switch arms against the right-hand contacts when the temperature rises above the desired value. This mode of operation is indicated by the legend appearing above the thermostats in the drawing, These damper v motors may be of a conventional type, in which, upon engagement of the thermostatic switch with its cold contact, for example, the damper motor moves its associated damper from closed to open position. As ,the damper reaches open position, the motor energizing circuit through the cold contact is broken, and contacts are closed which will permit the motor to be energized through the hot contact of the thermostat in order to move the'damper back to its closed position.

Operation When the parts are in the positions shown in the drawing the thermostat I! is calling for heat. As a consequence a circuit has been completed through conductor l88, contact I!) and switch arm l8, bimetallic element l1 and conductor |82 which has energized damper motor 4| so that damper 48 has been moved to its open position and cam 42 has moved switch-arm 43 into engagement with contact 45.

The engagement of the switch arm 43 with contact 45 completes an energizing circuit for the relay 68 and consequently moves the switch arms 62' and 63 into engagement with their respective contacts 64 and 65. The closure of switch arm 62 on contact 64 completes a circuit previously traced through the main supply valve 3| so that fuel is supplied to the furnace. Of course, if this circuit is broken by the safety switch 34 due to failure of the pilot flame or by the limit switch 3l' due to the presence of an excessive temperature in the bonnet of the furnace, this energizing circuit will not be completed. Assuming that conditions in the furnace are normal, however, the main supply valve 3| will be opened and fuel will be ignited at the main burner 38.

The temperature in the bonnet of the furnace will then rise causing the thermostat 35 to close the fan switch 35, thus completing an energizing circuit for the fan The relay 66 is energized at this time since switch arm 53 is closed on contact 54. The switch arm 68 is therefore held in its attracted position against the contact 69 so that the fan is energized through contact 69 and conductor 74. This results in the operation of the fan at its low speed.

If the thermostat 26 should now. move its switch arm 21 against the contact 28, thus calling for heat, a circuit would be completed to the damper motor 5| which would cause-the motor to move the damper 58 through degrees and the cam 52 through degrees. This would open the damper 58 to admit air to the zone I6. Operation of the cam 52 through 180 degrees would cause the switch arm 53 to be moved away from the contact 54 resulting in the deenergization of relay winding 61. The switch arm 68 would thereupon fall to its lower position, thus opening the low speed fan circuit through contact 59 and closing the high speed fan circuit through contact 18.

This operation would continue until one of the thermostats became satisfied, whereupon its associated switch arm would be moved to the right completing a circuit which would energize the damper motor to return the damper to its closed position and at the same time move the cam so as to permit the cam operated switch to move against its lower contact. This would complete an energizing circuit for the relay 66, thus lift- 1 having more than two zones.

is therefore peculiarly adapted to two zone ,re-

quirements.

While I have shown and described a specific embodiment of my invention, it should be understood that I am to be limited only by the scope of the appended claims. I claim as my invention: I 1. In a system for conditioning the air in two zones, in combination, air conditioning means, ducts for conveying conditioned air from said means to said zones, damper means in said ducts for individually controlling the delivery of air to each zone, separate motor means for operating the damper means of each zone, means in each zone responsive to a condition indicative of the need for a supply of conditioned air for controlling the operation of said motor means, means for. circulating 'air through said conditioning means and ducts to said zones at two difierent rates of flow, a first relay controlling the energization of said circulating means, a second relay controlling the rate of flowat which said circulating means is operated, a single-pole, doublethrow switch associated with each said damper means and operated simultaneously therewith 'by said motor means, a first contact for each said switch with which it engages when said dampers are open, a second contact for each switch with which it engages when said dampers are closed, an energizing circuit for said first relay including said switches and said first contacts in parallel; and an energizing circuit for said second relay including said switches and said second contacts in parallel.

2. In a system for heating the air in two zones, in combination, a heater, ducts for conveying heated air from said heater to said zones, damper means in said ducts for individually controlling the delivery of air to each zone, separate motor means for operating the damper means of each zone, a thermostat in each zone for controlling the operation of said motor means, means for circulating air from said heater to said zones at two different rates of flow, a first relay controlling the energization of said circulating means, a second relay controlling the rate of flow at which said circulating means is operated, a single-pole, double-throw switch associated with each said damper means and operated simultaneously therewith by said motormeans, a first contact for each said switch with which it engages when said dampers are open, a second contact for each switch with which it engages when said dampers are closed, an energizing circuit for said first rein combination, a heater, ducts for conveying heated air from said heater to said zones, damper means in said ducts for individually controlling the delivery of air to each zone, separate motor means for operating thedamper means of each zone, a thermostat in each zone for controlling the operation of said motor means, means for circulating air from said heater to said zones 'at two different rates of flow, a first relay controlling the energizationof said circulating means, a second relay controlling the rate of flow'at which said circulating means is operated, switch means associated with each said damper means and operated by said motor means so as to assume a first position when said damper means is open and a second position when said damper means is closed, an energizing circuit for said first relay lay including said switches and said first contacts in parallel, and an. energizing circuit for said secondv relay including said switches and said second contacts in parallel, said second relay when energized due to closure of any of said damper means permitting operation of said circulating means only at the lower of said two rates of flow, and when deenergized due to opening of all. said damper means permitting operation of said circulating means only at the higher of said two rates of flow.

3. In a system for heating the air in two zones,

including any of said switch means which is in its first position, and an energizing circuit for said second relay including any of said switch'means which is in its second position.

4. In a system for conditioning the air in two zones, in combination, air conditioning means, ducts for conveying conditioned air from said r means to said zones, damper means in said ducts for individually controlling the delivery of air to each zone, separate motor means for operating the damper means of each zone, means in each zone responsive to a condition indicative of the need for a supply of conditioned air for controlling the operation of said motor means, means for circulating air through said conditioning means and ducts to said zones at two different rates of flow, a first relay controlling the energization of said circulating means, a second relay controlling the rate of flow at which said circulating means is operated, said first relay when energized permitting energization of said circulating means and when deenergized preventing energization of said circulating means, said secondrelay when energized permitting operation of said circulating means at the lower of said two rates of flow, and when deenergized permitting operation of said circulating means atthe higher of said two rates of flow, and switch means responsive to the positions of said damper means for completing an energizing circuit for said first relay when any of said damper means is open and for completing an energizing circuit for said second relay when any of said damper means is closed.

5. In a system for conditioning the air in two zones, in combination, air conditioning means, ducts for conveying conditioned air from said means to said zones, damper means in said ducts controlling the rate of flow at which said circulating meansis operated, said first relay when energized permitting energization of said circulating means and when deenergized'preventing energization of said circulating means, switch means associated with each said damper means and operated by said motor means so as to assume a first position when said damper means is open and a second position when said damper means is closed, an energizing circuit for said first relay including any of said switch means which is in its first position, and an energizing circuit for said second relay including any of said switch means which is in its second position.

6.- In a system for conditioning the air in a plurality .of zones, in combination, air conditioning means, ducts for conveying conditioned air from said means to said zones, damper means in said ducts for individually controlling the delivery of air to each zone, separate motor means for operating the damper means of each zone, means in each zone responsive to a condition indicative of the need for a supply of conditioned air for controlling the operation of said motor means, means for circulating air through said conditioning means and ducts to said zones at two different rates of flow, a first relay controlling th energization of said circulating means and said air conditioning means, said relay when energized permitting energization of said two means, and when deenergized preventing energization of said two means, a second relay controlling the rate of flow at which said circulating means is operated, and switch means responsive to the pcsitionsof said damper means for completing an energizing circuit for said first relay when any of said damper means is open, and for controlling energization of said second relay in accordance with the number of said damper means which is open.

7. In a system for conditioning the air in a plurality of zones, in combination, air conditioning means, ducts for conveying conditioned air from said means to said zones, damper means in said ducts for individually controlling the delivery of air to each zone, separate motor means for operating the damper means of each zone, means in each zone responsive to a condition in dicative of the need for a supply of conditioned air for controlling the operation of said motor means, means for circulating air through said conditioning means and ducts to said zones at two diiierent rates of flow, a first relay controlling the energization of said circulating means and said air conditioning means, said relay when energized permitting energization of said two means, and when deenergized preventing energization of said two means, a second relay controlling the rate of flow at which said circulating means is operated, said second relay when energized permitting operation of said circulating means at the lower of said two rates of flow, and when deenergized permitting operation of said circulating means at the higher of said two rates of flow, and switch means responsive to the positions of said damper means for completing an energizing circuit for said first relay when any of said damper means is open and for completing an energizing circuit for said second relay when any of said damper means is closed.

CLARENCE W. NESSELL. 

